1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 /* 4 * This file provides wrappers with sanitizer instrumentation for bit 5 * locking operations. 6 * 7 * To use this functionality, an arch's bitops.h file needs to define each of 8 * the below bit operations with an arch_ prefix (e.g. arch_set_bit(), 9 * arch___set_bit(), etc.). 10 */ 11 #ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H 12 #define _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H 13 14 #include <linux/instrumented.h> 15 16 /** 17 * clear_bit_unlock - Clear a bit in memory, for unlock 18 * @nr: the bit to set 19 * @addr: the address to start counting from 20 * 21 * This operation is atomic and provides release barrier semantics. 22 */ 23 static inline void clear_bit_unlock(long nr, volatile unsigned long *addr) 24 { 25 kcsan_release(); 26 instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long)); 27 arch_clear_bit_unlock(nr, addr); 28 } 29 30 /** 31 * __clear_bit_unlock - Clears a bit in memory 32 * @nr: Bit to clear 33 * @addr: Address to start counting from 34 * 35 * This is a non-atomic operation but implies a release barrier before the 36 * memory operation. It can be used for an unlock if no other CPUs can 37 * concurrently modify other bits in the word. 38 */ 39 static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) 40 { 41 kcsan_release(); 42 instrument_write(addr + BIT_WORD(nr), sizeof(long)); 43 arch___clear_bit_unlock(nr, addr); 44 } 45 46 /** 47 * test_and_set_bit_lock - Set a bit and return its old value, for lock 48 * @nr: Bit to set 49 * @addr: Address to count from 50 * 51 * This operation is atomic and provides acquire barrier semantics if 52 * the returned value is 0. 53 * It can be used to implement bit locks. 54 */ 55 static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr) 56 { 57 instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long)); 58 return arch_test_and_set_bit_lock(nr, addr); 59 } 60 61 /** 62 * xor_unlock_is_negative_byte - XOR a single byte in memory and test if 63 * it is negative, for unlock. 64 * @mask: Change the bits which are set in this mask. 65 * @addr: The address of the word containing the byte to change. 66 * 67 * Changes some of bits 0-6 in the word pointed to by @addr. 68 * This operation is atomic and provides release barrier semantics. 69 * Used to optimise some folio operations which are commonly paired 70 * with an unlock or end of writeback. Bit 7 is used as PG_waiters to 71 * indicate whether anybody is waiting for the unlock. 72 * 73 * Return: Whether the top bit of the byte is set. 74 */ 75 static inline bool xor_unlock_is_negative_byte(unsigned long mask, 76 volatile unsigned long *addr) 77 { 78 kcsan_release(); 79 instrument_atomic_write(addr, sizeof(long)); 80 return arch_xor_unlock_is_negative_byte(mask, addr); 81 } 82 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H */ 83